Digital Media Technology

Digital Media Technology Week 10

PHP • Interactive and dynamic webpages • PHP: hypertext preprocessor • Embedded in HTML files • Stored in a file with .php extension • Code surrounded by <?php and ?> • Variables start with a dollar sign, e.g. $name • Number and strings • Operators: + - * /

Examples • Search engine • Index of names • Web form for the creation of TEI documents

Digitale Bibliotheek Nederlandse Literatuur (DBNL) TEI PHP

Crowdsourcing

Human Programmer Programming language, e.g. PHP Language interpreter Computer Machine Language 0101100101010

Computer languages are artificial languages: Grammar & Syntax first, then usage. Natural languages: Usage, grammars are reconstructed • Strictness and consistency is necessary for development of interpreters

Programming takes place in two steps: • Algorithmic design • Coding • Algorithms can be visualised in Program Structure Diagrams

Validation of user input: example read input contains ‘@’ ? N Y write ‘email is correct’ write ‘email is not valid’

HTML form PHPscript User information

HTML Form Elements <input type="text"</input> <input type="submit" value=" GO ">

A Form in HTML <html> <head> <title>Databases and Webprogramming</title> </head> <body bgcolor="#99CCFF" text="#000000"> <form action="action.php" method="get"> Enter e-mail address : <br><input type="text" name="email" size="25"> <BR> <input type="submit" value=“CHECK!"> </p> </form> </body> </html>

method=“get” : http://www.bookandbyte.org/2012-2013/ action.php?email=info@leidenuniv.nl method=“post” : http://www.bookandbyte.org/2011-2012/action.php

A Form in HTML <html> <head> <title>Databases and Webprogramming</title> </head> <body bgcolor="#99CCFF" text="#000000"> <form action="action.php" method="get"> Enter e-mail address : <br><input type="text" name="email" size="25"> <BR> <input type="submit" value=“CHECK!"> </p> </form> </body> </html>

Form data processed by PHP script • A so-called array will be created, depending on the method specified:$_GET or $_POST ; • Names specified can be used to refer to the values, e.g.:$_GET[“email”] ; $_POST[“email”] ;

action.php : <html><head><title>DBWP</title></head> <body bgcolor="#99CCFF" text="#000000"> <?php $name = $_GET[“name”] ; print "<p>Welcome, $name !</p>" ; ?> </body> </html>

Conditional Selection <xsl:if test="place"> <xsl:value-of select="place"/> <xsl:if test="year"> <xsl:text>, </xsl:text> </xsl:if></xsl:if> <xsl:if test=“year"> <xsl:value-of select=“year"/> </xsl:if>

Conditions in PHP if ( condition ) { [ code block 1 ] } else { [ code block 2 ] }

$email = “info@leidenuniv.nl” ; if ( preg_match( “/@/”, $email) ) { print “Email is correct.” ; } else { print “Email is not valid. ; }

Multiple choices read language English? N Y German? Write ‘Welcome!’ Y N French? Write ‘Wil-kommen!’

Conditional Structures: Selection if ( condition ) { [ code block 1 ] } elseif ( condition ) { [ code block 2 ] } else { [ code block 3 ] }

HTML Pull-down menu <select> <option>Select...</option><option value="">option 1</option><option value="">option 2</option></select>

Pull-down menus <form action=“welcome.php" method="get"> <select name="language"> <option> -- Choose a language -- </option> <option value="dut">Nederlands</option> <option value="eng">English</option> <option value="fre">Français</option> <option value="ger">Deutsch</option> <option value="ita">Italiano</option> </select> <BR> <input type="submit" value="GO!"> </p> </form> this file in a browser

$language = $_GET["language"] ; if ( $language == "dut" ){ print "Welkom op deze website!"; }elseif ( $language == "eng" ){ print "Welcome to this website!"; } elseif ( $language == "fre" ){ print "Bienvenue sur le site!"; }elseif ( $language == "ger" ){ print "Willkommen auf der Website!"; }elseif ( $language == "ita" ){ print "Benvenuto al questo site!"; }else{ print "Please choose a language first!"; }

$title = "Waiting for Godot"; $titles = array ("Waiting for Godot", "Endgame", "Happy Days", “Krapp’s Last Tape" );

Arrays • Used to define a collection / a list • Can be declared with the array()function <?php $titles = array ("The Life of Dr. Boerhaave", "First Principles of Typography", "Florentissima Brittanniae Urbs ", "Digital Access to Book Trade Archives" ) ; ?>

Use of the array() function in this way will create an automatic index

Addressing elements in the array <? $books = array ( "The Life of Dr. Boerhaave", "First Principles of Typography", "Florentissima Brittanniae Urbs", "A relation of a Voyage to the Army") ; print $books[1] ?>

An indexed array : $capitals = array( "Italy"=> "Rome", "Luxembourg"=> "Luxembourg", "Belgium"=> "Brussels", "Denmark"=> “Copenhagen", "Finland"=> "Helsinki", "France"=> "Paris", "Slovakia"=> "Bratislava", "Slovenia"=> "Ljubljana", "Germany"=> "Berlin” ) ;

Addressing an element in an indexed array : $capitals = array( "Italy"=> "Rome", "Luxembourg"=> "Luxembourg", "Belgium"=> "Brussels” ) ; print $capitals["Italy"] ; // this will print "Rome"

Counting the number of elements in an array <? $books = array ("The Life of Dr. Boerhaave", "First Principles of Typography", "Florentissima Brittanniae Urbs", "Digital Acces to Booktrade Archives") ; $number = count($books) ; ?>

Navigating arrays $books = array("Heart of Darkness", "The Picture of Dorian Grey", "The Last September" ); foreach ($books as $b) { print " <p> $b </p> “ ; }

"We will encourage you to develop the three great virtues of a programmer: laziness, impatience, and hubris." (Larry Wall, Programming Perl)

Digital Media Technology